VEGFA Status as a Predictive Marker of Therapy Outcome in Metastatic Gastric Cancer Patients Following Ramucirumab-Based Treatment

Abstract

Metastatic gastric cancer (mGC) often has a poor prognosis and may benefit from a few targeted therapies. Ramucirumab-based anti-angiogenic therapy targeting the VEGFR2 represents a milestone in the second-line treatment of mGC. Several studies on different cancers are focusing on the major VEGFR2 ligand status, meaning VEGFA gene copy number and protein overexpression, as a prognostic marker and predictor of response to anti-angiogenic therapy. Following this insight, our study aims to examine the role of VEGFA status as a predictive biomarker for the outcome of second-line therapy with Ramucirumab and paclitaxel in mGC patients. To this purpose, the copy number of the VEGFA gene, by fluorescence in situ hybridization experiments, and its expression in tumor tissue as well as the density of micro-vessels, by immunohistochemistry experiments, were assessed in samples derived from mGC patients. This analysis found that amplification of VEGFA concomitantly with VEGFA overexpression and overexpression of VEGFA with micro-vessels density are more represented in patients showing disease control during treatment with Ramucirumab. In addition, in the analyzed series, it was found that amplification was not always associated with overexpression of VEGFA, but overexpression of VEGFA correlates with high micro-vessel density. In conclusion, overexpression of VEGFA could emerge as a potential biomarker to predict the response to anti-angiogenic therapy.

Keywords: VEGFA; anti-angiogenic therapy; metastatic Gastric Cancer; micro-vessels; predictive marker.

Figure 1

VEGFA expression and micro-vessel density in Control Disease GC patients. (a–c) Visualization of VEGFA gene locus status by FISH. (a) represents gene amplification, (b) polysomy and (c) diploid status. The green and red signals correspond to the VEGFA and reference centromere 6 gene region, respectively. (d–f) VEGFA immunostaining in tumor tissues. The three images all depicted VEGFA’s overexpression. Representative tumor cells overexpressing VEGFA were indicated by red arrows. (g–i) Micro-vessel density in tumor tissues evaluated by CD34 immunostaining. The three images all showed CD34′s overexpression.

Figure 2

VEGFA expression and micro-vessel density in Rapid Progression GC patients. (a–c) Visualization of VEGFA locus status by FISH. (a) gene amplification, (b) polysomy and (c) the diploid status, were represented (Examples of nuclei with VEGFA copy numbers >2 are indicated by the red arrows). The green and red signals correspond to the VEGFA and reference centromere 6 gene region, respectively. (d–f) VEGFA immunostaining in tumor tissues. The three images depicted tumor cells not overexpressing VEGFA. (g–i) Micro-vessel density in tumor tissues evaluated by CD34 immunostaining. The three images showed low CD34 overexpression.

Figure 3

Correlation plot with single data (dots) between tissue VEGFA and CD34 expression. Spearman Rho correlation between IHC VEGFA and IHC CD34 scores in the total patient cohort in red (a) and in Control Disease in blue (b) and Rapid Progression in green (c) groups.

Figure 4

Correlation plot with single data (dots) between VEGFA or CD34 expression and progression-free survival (PFS). Spearman’s Rho correlation between PFS and IHC VEGFA score in green (a) and IHC CD34 score in red (b) in the total cohort of mGC patients.